Process for the industrial manufacture of electrolytic iron.



UNITED STATES PATENT oFFro ANTHELME BOUCHER, or PRILLY-GHASSEUR, swrrznar.lu'vi), ASSIGNOR r0 SOCIEI'E LE FER, SOCIETE ANONYME, or GRENOBLE, FRANCE.

PROCESS FOR THE INDUSTRIAL MANUFACTURE OF ELECTROLYTIC .IROLN.

No Drawing.

Specification of Letters Patent.

- Patented Feb. 3,1914.

Application filed March 22, 1913. Serial No. 756,243. v

To all whom it may concern:

Be it known that I, ANTHELME BoUcHER, a citizen of Switzerland, residing at Prilly- Chasseur, in the Canton of Vaud, Switzerland,- and whose post-office address is Les Passiaux, Prilly-Ghasseur, Canton of Vaud, Switzerland, have invented a new and use- .ful Process for the Industrial Manufacture of Electrolytic Iron, which is fully set forth in the following specification.

This invention relates to a process for industrial manufacture of electrolytic iron. In order that such manufacture should be really industrial, it is necessary to be able to work with currents of great density while obtaining a product of very good'quality and operating at a maximum efiiciency. To that end it is necessary to observe various special conditions. First. of' all the electrolyte is prepared and it is constituted by a solutionv of ferrous chlorid or of ferrous sulfate or of a mixture of ferrous salts. If the electrolyte which thus has a green color, is used without any preliminary treatment, only a deposit of irregular character and of no commercial value is obtained.

In order to obtain a smooth, compact, homogeneous deposit that can be utilized after a simple annealing, it is first advisable to stir the electrolyte, either in a special cell or not, for instance by simple rotation of the anode, so as to produce an oxidizing action of the air, at the samet-ime as the electrol .sis phenomenon proper. The iron salts being very easily oxidizable in the air, the composition of the bath is modified, and an oxychlorid of iron is produced which reacts on thehydrogen in bubbles .adhering to the cathode, and thereby eliminates the cause of the bad quality of the deposits. In similar manner, ferrous sulfate yields basic sulfates having a depolarizingaction. Si-' multaneously with this formation of oxychlorid, the oxygen of theair produces also ferric chlorid which, at the expense of the apparatus itself or of the iron deposits on the cathode, is again converted into ferrous chlorid. In order to avoid this loss of efliciency and the corrosion of the apparatus,

the electrolyte is caused to circulate over iron shavings in an independent cell.

The solution will be in good condition when it has acquired a clear'chestnut brown color and no'longer foams. It can then be used for regular industrial worklng. It is body of the metal.

lowing conditions of working:

1. To rotate the cathode at a tangential speed which varies in accordance with the density of the current. When working with very low amperage, the rotation may be very slow or is even unnecessary, but with moreover necessary to comply with the fel strong currents such as are required for industrial purposes it is necessary to increase the speed: the greater the amperage, the more rapidly it is necessary to rotate the cathode, without however exceeding a practical speed,.in order to avoid complications of the apparatus, the drawbacks of centrifugal force, etc. By Way of example, it may be stated that at 800 amperes per square meter, the tangential speed should be preferably 120 meters per second.

2. Thetemperature must be regulated in accordance with a given density of current, and maintained 'absolutel constant. It is possible to obtain a goo deposit cold by working with very small densities of current, but if the amperage increases, it is necessary to increase also the temperature, without however reachingthe boiling temperature of the liquid, for at that moment there would be formed in the interior of the electrolyte, gas or steam bubbles which necessary to keep the temperature very constant in order to obtain a very uniform deposit. In fact, electrolytic deposits always contain a certain proportion of various gases which produce fairly strong tensions in the By varying the temperature, the said inner tensions or strains are varied, and the'result is frequently a cracking and a separation of the deposit which renders it useless.

3. The concentration must be regulated in accordance with the depolarizing power of the liquid, and the said concentration must be kept absolutely constant. In order to regulate the concentration, it is necessary to take into account thedepolarizing power of the liquid. In fact, when the concentration of the liquid .varies, there is a variable electrolysis of the water. In other words, the quantity of -hydrogen at the cathode varies, and this hydrogen has an injurious effect or not, according to the depolarizing power of the liquid. It is therefore necessary, for a given apparatus to adopta suitable concentration, for instance 40 Baum,

and to keep the said concentration constant. Otherwise there will be irregularities in the deposit and the iron will be no longer suitable for industrial use. The loss of liquid can be replaced by pouring into the apparatus in a continuous manner a jet of fresh liquid, instead of adding the said liquid to the electrolyte from time to time in comparatively large quantities.

4. Finally, it is advisable to keep the peed of circulation of the electrolyte around the anode as high as possiblef It has been found in fact that the greater the speed of circulation, the lower the proportion of phosphorus.

, By observing the conditions above referred to, excell ent results are obtained:

In order to maintain the liquid at the proper degree of oxidation, which is recognized, as already stated, by the clear chestnut color and the absence of foaming, there is preferably used an apparatus provided with a lid with adjustable opening enabling the admission of air to be increased or decreased at will. It would be possible, for the same purpose, to inject air into the liquid, the quantity of the said air being regulated by means of a cock. This obviates the drawbacks due to the use of apparatus with closed vessel, that isto say, absolutely protected from air, which require constant addition of a special depolarizer, and of apparatus with open vessel which leave the whole surface of the electrolyte in contact with the surrounding air. By the regulated action of the air, is obtained the formation of a certain quantity of oxychlorid or other basic salt of iron which forms a depolarizer, and on the other hand, is avoided the formationof an excess of ferric salts which re duce the efiioiency. In these conditions, it is possible to Work with currents of 1,000 a1nperes and more per square meter, and to obtain a very homogeneous product with an average ampere efficiency of 98%.

Claims:

1. In a process of electrodepositing iron, the step of preparing the electrolyte which consists in subjecting a dissolved ferrous salt to limited oxidation, until it acquires a clear brown color and ceases to foam.

2. In a process of electrodepositing iron, the step which consists in effecting depolarization of the cathode by dissolved basic iron salts.

3. In a process of electrodepositing iron, the step which consists. in regulating the access of air to the electrolyte to produce therein sufficient basic iron salts to effect depolarization of the cathode.

4. In a process of electrodepositing iron, the steps which consist in regulating the access of air to the electrolyte to produce therein suflicient basic iron salts to effect depolarization of the cathode, and circulating the. electrolyte in contact with metallic iron to reduce coincidentally-formed ferric salts.

5. A process of electrodepositing iron, consisting in subjecting a dissolved ferrous salt to limited oxidation, and thereafter electrodepositing iron therefrom upon a rotating cathode, while maintaining the electrolyte at a constant temperature and concentration, and so regulating the access of airto the electrolyte as to produce therein sufficient basic salts of iron to effect depolarization of the cathode.

' In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

ANTHELME BOUCHER.

Witnesses:

EMILE LEDRET, LUomN MEMMINGER. 

